1. Field of the Invention
The present invention relates to a lens position adjusting mechanism for positioning an illumination light region accurately in an image-forming region of an image display element, and to a projection-type display device utilizing the mechanism.
2. Description of Related Art
Conventionally, a projection-type display device, typified by a projector and the like, includes a mechanism for adjusting the position of a lens placed in an illumination optical system so as to position illumination light from a light source accurately in an image-forming region of an image display element.
FIG. 7 is a perspective view showing an example of such a lens position adjusting mechanism described in JP 2000-330194A. A lens position adjusting mechanism 300 includes a fixing frame 320, an attachment frame 330, and screws 340a, 340b as adjusting members.
The attachment frame 330 with a superimposed lens 150 attached thereto is supported by the fixing frame 320. The fixing frame 320 is fixed to an upper light guide (not shown) that is a housing for optical components. The screws 340a, 340b function as adjusting members for adjusting the attachment position of the superimposed lens 150 by moving the attachment frame 330 with respect to the fixing frame 320.
In adjusting a lens position, when the screw 340a is turned clockwise, the attachment position of the superimposed lens 150 moves upward. Conversely, when the screw 340a is turned counterclockwise, the attachment position of the superimposed lens 150 moves downward. The same turning operation of the screw 340b can move the attachment position of the superimposed lens 150 horizontally.
However, in the conventional configuration described above, it requires a great deal of time for adjustment since two screws 340a, 340b are turned separately.